Drill bit



March 12, 1963 v l. J. BERscHElD 3,080,934

DRILLBIT Filed sept. 21, 1959 United States Patent O 3,080,934 DRILL BIT Irvine J. Berseheid, Box 8, Bissett, Manitoba, Canada Filed Sept.- 21, 1959, Ser. No. 841,062 S Claims. (Cl. 175410) My invention relates to new and useful improvements in drill bits, particularly to drill bits containing tungsten carbide inserts.

Conventional drill bits are tapered so that the cutting end of the bit is greater in diameter than the end by which the bit is attached to the associated drill rod. This taper s provided to prevent Abinding within the drill hole and is variable to best counteract the variable conditions encountered in -drilling rock or the like in conjunction with drilling machines which alternately rotate and percussively force the bit into the rock being drilled.

When drilling in rock of an abrasive nature, the cutting and reaming edges of the bit inserts become worn and fa condition known tas antitaper is formed on the outer sides or corners of the insert so that -the cutting end of the bit becomes slightly smaller in diameter than the diameter of the bit immediately `adjacent thereto.

If too much antitaper is allowed to wear on the sides of the bit, the drilling speed Iis reduced considerably because of the wedging action of the bit in the hole and because excessive bit surface area is contacting the wall of the hole.

It is conventional to resharpen such drill bits but in order to rest-ore the original taper, as well as to sharpen the cutting faces, the entire overall dimensions of the drill bit are reduced.

Restoring the original taper is undertaken conventionally by what is known as gauge Igrinding and when gauge grin-ding is practised, bits must all be sized Ivand marked so that they can be identilied by the driller to enable him to utilize the proper size rof bit within the hole Ibeing drilled.

Also to restore the original taper it will be appreciated that this grinding reduces the diameter of the unworn as Well as the worn parts of the bit. I-f gauge grinding is not undertaken and only the face of the bit is sharpened, excessive carbide must be ground away to bring the bit to a sharp condition and this results in a reduce-d footage drilled per bit and `a rise in cost per lfoot drilled.

The principal object of this invention is to provide a drill bit which will limit the distance that antitaper can be worn for any given amount of drilling thereby limiting the wedlging action and increasing the penetration rate.

Another purpose of the invention is to provide a device of the chanacter herewithin described in which the bit can be resharpened by grinding only the face of the bit without grinding away an excessive amount of the carbide insert.

A still `further object of my invention is to provide a device of the character herewithin described in which the bit will not require gauge grinding, and therefore it is possible to judge visually the comparative cutting face diameters of any given size of bits by the depth of the insert remaining instead of the bits having to be measured and sorted accordingly.

A still further object of the invention is to provide a device of the character herewithin described which will produce more feet drilled per unit depth of carbide than conventional bits. This is occasioned because in sharpening, less useful carbide needs t-o be ground away from the face of the insert to bring them to a sharp and drillable condition than is the case with a conventional bit.

I overcome the disadvantages of conventional bits by providing the outer face of the insert with a plurality of ICC stepped zones, decreasing in diameter from the drilling edge thereof, so that all that needs to be done when sharpening, is to grind off the excess material on the cut-ting faces until they are in a sharp and drillable condition. Thereiore by counting the number of zonesit will be appreciated, of course, that the effective diameter of the bit can readily be judged rather than having to measure same.

Also drill bit manufacturers only guarantee their bits if antitaper is not lallowed to exceed a specific amount in :order to prevent pressure from forcing the inserts out of their receiving slots. By spacing the stepped zones not more than this specied amount apart, even if severe antitaper occurs during drilling, itl reaches the next step or zone and is automatically relieved thus preventing the antitaper from exceeding the specified amount. v

With the foregoing objects in View, fand such other objects and advantages as will become apparent to those skilled in the art to which this invention relates as this specication proceeds, my invention consists essentially in the arrangement and construction of parts all as hereinafter more particularly described, reference being had to the accompanying drawings in which:

FIGURE l is a top plan view of a bit showing the four inserts therein.

FIGURE 2 is a side elevation of FIGURE l with the inserts sectioned for clarity and showing my invention incorporated therein.

FIGURE 3 is an enlarged fragmentary side section of one of my inserts showing one embodiment thereof.

FIGURE 4 is a view similar to FIGURE 3 but showing an `alternative embodiment.

FIGURE 5 is a view similar to FIGURE 4 but showing a still further embodiment.

FIGURE 6 is an enlarged fragmentary front elevation of one of my inserts.

FIGURE 7 is an enlarged fragmentary front elevation of one of my inserts showing an alternative embodiment.

FIGURE 8 is an enlarged fragmentary front elevation of one of my inserts showing another embodiment.

FIGURE 9 is an enlarged fragmentary front elevation of one of my inserts showing a still further embodiment.

In the drawings like characters of reference indicate corresponding parts in the different figures.

Proceeding therefore to describe my invention in detail, it should be noted that although I show a four winged bit in the drawings, Inevertheless my invention is Kapplicable to any type of drilling bit using tungsten carbide inserts or the equivalent.

Reference character 10 illustrates the end of the bi-t body 11 being provided with lfour wings 12 within which are secured by conventional means such as welding or brazing, tungsten carbide inserts collectively designated 13.

These inserts are provided with cutting edges 15 which extend radially from adjacent the center 16 of the drill bit and these inserts are provided with outer Walls L17 being curved as at 18 in the usual manner and inclining from the cutting edge at an acute angle.

A plurality of zones 20, 21, 22. and 23 are formed on the outer wall 17 of the cutting inserts and it will be noted that these zones are :stepped inwardly progressively from the zones 20 nearest the cutting edge 15 to the lower-most zones 23, which is furthest from the cutting edge 15.

It will also be noted that the walls I19 of the drill bit body taper inwardly from the end of the bit body |11 thereof in order to provide the necessary clearance when drilling through rock or other material.

The joining surfaces 24 between the adjacent zones may be varied as shown in FIGURES 3, 4 and 5.

In FIGURE 3, these joining sur-faces are arcuately curved to provide a relatively slow transition of the dimension between adjacent zones.

In FIGURE 4, the joining surfaces 24 are substantially at right angles to the zones and in FIGURE 5, these joining surfaces are shown inclined depending upon the method of manufacture iand choice of design.

FIGURES 7, 8 and 9 show alternative embodiments of the zones as distinguished from the zones shown in the remainder of the drawings.

In FIGURE 7, the zones incline upwardly from one side of the curved end to the other.

FIGURES 8 and 9 show the zones arcuately curved, convexly in FIGURE 8 and concavely in FIGURE 9 with respect to the drawings. These variations may be used depending on specific oper-ation requirements or manulfacturing techniques.

In operation the drill bit is attached to the conventional drill rod (not illustrated) and drilling proceeds. Wear normally occurs on the cutting edges 15 and on the outer corners 25 of the insert un-til such time as the profile of the section is similar to that shown by the dotted line-26 in FIGURE and some antitaper has been formed. At this stage it is necessary to grind the drill bit until the profile is similar to the dotted line 27 which has restored the bit to a drillable condition with the removal of the minimum -amount of material. Furthermore this sharpening has been accomplished without the necessity of gauge grinding without the necessity of measuring the resultant diameter and can be repeated successively as wear occurs until the final zone is reached at which time of course, the life of the drill bit has `been extended considerably.

Since various modifications can be made in my invention as hereinabove described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit yand scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustra-tive only and not in a limiting sense.

What I claim as my invention is:

1. A drill bit insert adapted to be secured into a drill bit, comprising in combinations a cutting edge, and a curved outer Wall extending .at an angle therefrom, the angle between said cutting edge and said outer wall Ibeing 90 degrees or less, and a plurality of stepped zones formed on said outer wall, said zones being stepped inwardly progressively from the zone nearest .to said cutting edge to the zone |farthest therefrom, each zone Ibeing connected to the adjacent zone by a substantially radially, inwardly extending joining surface, each of said zones including a por-tion of said curved outerrwall, said portion also forming an angle of degrees or less with said cutting edge, said stepped zones facilitating the sharpening and sizing of the drill bit by providing a plurality of predetermined cutting diameters on the drill bit.

2. A drill Ibit comprising in combination a drill bit body, and at least one insert secured therein, said insert having a cutting edge formed thereon, and a curved outer wall extending lat an angle from said cutting edge, the angle between said cutting edge and said curved outer wall being 90 degrees or less, Aand a plurality of stepped zones formed on said curved outer wall, said zones being stepped inwardly progressively from the zone nearest to said cutting edge to the zone farthest therefrom, each zone being connected to the adjacent zone yby a substantially radially, inwardly extending joining surface, each of said zones including a portion of said curved outer Wall, said portion also forming an angle of 90 or less with said cutting edge, said stepped zones facilitating the sharpening and sizing o-f said drill bit by providing a plurality of predetermined cutting diameters on said drill bit.

3. The device according to claim 1 in which the joining surface between adjacent zones is substantially at right angles to the adjacent zones.

4. The device according to claim 2 in which the joining surface between Aadjacent zones is substantially at right :angles to the adjacent zones.

5. The `device according to claim l n which the joining surface between adjacent zones is arcuately curved relative to the longitudinal extent of the zone.

6. The device according to claim 2 in which `the joining surface between adjacent zones is arcuately curved relative to the longitudinal extent of the zone.

7. The device according to claim l in which the joining surface between adjacent zones is inclined circumferentially.

8. The device according to claim 2 in which the joining surface between adjacent zones is inclined ycircumferentially.

References Cited in the file of this patent UNITED STATES PATENTS 1,359,318 Bernay Nov. 16, 1920 2,131,056 Lind Sept. 27, 1938 2,393,550 Meinert Jan. 22, 1946 2,588,782 Waterland Mar. 11, 1952 

1. A DRILL BIT INSERT ADAPTED TO BE SECURED INTO A DRILL BIT, COMPRISING IN COMBINATIONS A CUTTING EDGE, AND A CURVED OUTER WALL EXTENDING AT AN ANGLE THEREFROM, THE ANGLE BETWEEN SAID CUTTING EDGE AND SAID OUTER WALL BEING 90 DEGREES OR LESS, AND A PLURALITY OF STEPPED ZONES FORMED ON SAID OUTER WALL, SAID ZONES BEING STEPPED INWARDLY PROGRESSIVELY FROM THE ZONE NEAREST TO SAID CUTTING EDGE TO THE ZONE FARTHEST THEREFROM, EACH ZONE BEING CONNECTED TO THE ADJACENT ZONE BY A SUBSTANTIALLY, RADIALLY, INWARDLY EXTENDING JOINING SURFACE, EACH OF SAID ZONES INCLUDING A PORTION OF SAID CURVED OUTER WALL, SAID PORTION ALSO FORMING AN ANGLE OF 90 DEGREES OR LESS WITH SAID CUTTING EDGE, SAID STEPPED ZONES FACILITATING THE SHARPENING AND SIZING OF THE DRILL BIT BY PROVIDING A PLURALITY OF PREDETERMINED CUTTING DIAMETERS ON THE DRILL BIT. 